here's where you need to do some research and planning. a turbo setup requires planning for two reasons:
1) reliability. you dont want an under-built engine for the power goal you choose.
2) results. if you want the desired results, youll need to pick specific parts that will work together to get you exactly what you want.
now, that being said, here are the general steps taken to put together a reliable (and suitable) turbo setup:
1)choose a power goal
2)choose parts to support that power goal (example: 500whp is not a good number to be running on stock pistons and rods!)
3)choose how you want that power to be delivered (do you want the car to dive straight into the powerband? or do you want something that comes on later in the RPM's?)
4)research turbochargers (have a whole thread on it here, and theres TONS of articles on how to select the proper turbo based upon engine speed, load, etc all over the internet)
5)just when you think youve researched enough, research some more and compare with other people's setups that have already been dyno'd.
6) buy your parts and assemble it.
obviously this is just a basic guideline but im not going to spoon feed you the information that is already written all over the web.
in regards to compression, that is something that you will figure out during the research process. higher compression generally means quicker spool time and more power on less boost, but can be tricky/dangerous to tune and higher pressure levels due to higher cylinder pressures.
i wouldnt worry about where to send your head for a port and polish until you do some research and figure out EXACTLY what you want from this build.